update: freedom found, natural selection theory pushed aside

One way it was 'tested' was making a prediction about a fossil that was going to be found. According to the TOE, there was a transitional form between fish and amphibians that lived in a certain time period.
This group of scientists went to an area whose rocks were the proper age, and were the proper environment (shallow seaside), and found that fossil.That was one way.. there were many other ways too. Forensic's is a very important part of biology though.